Emergence of linguistic diversity in the lab

There is a huge amount of linguistic diversity in the world. Isolation and drift due to cultural evolution can explain much of this, but there are many cases where linguistic diversity emerges and persists within groups of interacting individuals. Previous research has identified the use of linguistic cues of identity as an important factor in the development of linguistic diversity (e.g. Nettle, 1999). Gareth Roberts looks at this issue with an experimental paradigm.

This experiment was a game where individuals had to trade commodities in a series of rounds. At each round, individuals were paired up either with a team-mate or a competitor, though the speaker’s true identity was hidden. Players were given random resources, but scored points based on how ‘balanced’ their resources were after trading (that is, you were punished for having much more meat than corn, for example). A commodity given to another individual was worth twice as much to the receiver as to the donor.

Players could only interact through an ‘alien’ language via an instant-messaging system. Prior to the game, individuals learned an artificial language which they were to use in these interactions. All participants were initially given the same starting language. There were several conditions that manipulated the frequency with which you interacted with your team-mate and whether the task was competitive or co-operative. In the co-operative condition, four players were considered as part of the same team and the task was to get a high a score as possible. In the competitive condition the four players were split into two groups and the task was to score more than the other team. In this condition, then, the main task was to identify whether your partner was a co-operator or a competitor.

The results showed that, if players interacted frequently enough with their team-mates and were in competition with another group, then linguistic diversity emerged. Over the course of the game each team developed its own ‘variety’, and this was used as a marker of group identity. For example, in one game two forms of the word for ‘you’ arose. Players in one team tended to use ‘lale’ while players in the other team tended to use ‘lele’, meaning that players could tell group membership from this variation. Thus, linguistic variation arose due to the linguistic system evolving to encode the identity of the speakers.

The diversity seemed to arise both from drift and intentional change, both of which have been documented in the sociolinguistic literature. Roberts suggests that linguistic markers make good social markers because they are costly to obtain (so difficult for free-riders to fake), salient and flexible enough to cope with changing group dynamics. In the next post, I’ll be thinking about a similar experiment looking at how linguistic variation might arise in a co-operative scenario.